NASA's Mars rover Curiosity has taken the first nighttime images of a rock, using the camera on its robotic arm.

Scientists used the rover's Mars Hand Lens Imager (MAHLI) instrument fitted with four white and two ultraviolet LEDs to take a close-up nighttime look at a rock target called "Sayunei". The rover scuffed the rock with its wheels to clear off the dust and examine it closely.

The idea behind examining the rock under the illumination of ultraviolet vision was to look for the presence of fluorescent minerals that could not be detected using normal white lights or sunlight, but could be seen using UV light, according to NASA scientists. "The purpose of acquiring observations under ultraviolet illumination was to look for fluorescent minerals," MAHLI principal investigator Ken Edgett, of Malin Space Science Systems, San Diego, said in a statement.

"These data just arrived this morning. The science team is still assessing the observations. If something looked green, yellow, orange or red under the ultraviolet illumination, that'd be a more clear-cut indicator of fluorescence."

The location of the rock is very close to the site, where the rover will start to drill its first rock in the coming weeks. Curiosity landed on the Gale Crater more than five months ago to detect if the Red Planet has offered environmental conditions favorable for microbial life.

There is already a growing body of evidence suggesting that life may have once thrived on Martian soil in the distant past. Last September, Curiosity found some interesting evidence showing that an ancient streambed once flowed on the surface of Mars.

More recent evidence was obtained by NASA's Mars Reconnaissance Orbiter (MRO), launched in 2005 to pick up signs that could show that water persisted on the planet for a long period of time. New images of the McLaughlin Crater on Mars, taken by MRO, show the presence of carbonate and clay minerals (elements that form through interaction with water) on flat rocks. The evidence suggests that the McLaughlin Crater, which is currently dry, had a wet underground environment in the past.